There is an initialized version of "battery" that uses a "B" hand.
This is a "Signed English" version of battery. I see it being used from
time to time with Deaf kids that use hearing-aids, but I really don't recommend
using this sign.
The "ASL way"
to sign "battery" is to use the sign for electricity.

If you sign "HEARING-AID ELECTRICITY" it is obvious that you are talking about a
"hearing-aid battery." So there usually no real need to ever use
the initialized version of "battery" shown below.

BATTERY: (initialized version) (not recommended)

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